Preparation of 6-aminocaproic acid from 5-formyl valeric acid

ABSTRACT

The invention relates to a method for preparing 6-aminocaproic acid (hereinafter also referred to as ‘6-ACA’) using a biocatalyst. The invention further relates to a method for preparing E-caprolactam (hereafter referred to as ‘caprolactam’) by cyclising such 6-ACA. The invention further relates to a host cell, a micro-organism, or a polynucleotide which may be used in the preparation of 6-ACA or caprolactam.

This application is a divisional of U.S. patent application Ser. No.15/599,314, filed May 18, 2017, which is a divisional of U.S. patentapplication Ser. No. 14/105,705, filed Dec. 13, 2013, now issued U.S.Pat. No. 9,663,805, issued Jun. 8, 2017, which is a continuation of U.S.patent application Ser. No. 12/921,733, filed Dec. 21, 2010, now issuedU.S. Pat. No. 8,673,599, issued Mar. 18, 2014, which is a U.S. NationalStage Application under 35 U.S.C. § 371 of International PatentApplication No. PCT/NL2009/050117, filed Mar. 11, 2009, which claims thebenefit of European Patent Application No. 08152584.2, filed Mar. 11,2008, the entire contents of which are each incorporated herein byreference.

The instant application contains a Sequence Listing which has beensubmitted in ASCII format via EFS-Web and is hereby incorporated byreference in its entirety. Said ASCII copy, created on Aug. 20, 2018, isnamed 12956-454-999_Sequence_Listing and is 249,788 bytes in size.

The invention relates to a method for preparing 6-aminocaproic acid(hereinafter also referred to as ‘6-ACA’). The invention further relatesto a method for preparing ε-caprolactam (hereafter referred to as‘caprolactam’) from 6-ACA. The invention further relates to a host cellwhich may be used in the preparation of 6-ACA or caprolactam.

Caprolactam is a lactam which may be used for the production ofpolyamide, for instance nylon-6 or nylon-6,12 (a copolymer ofcaprolactam and laurolactam). Various manners of preparing caprolactamfrom bulk chemicals are known in the art and include the preparation ofcaprolactam from cyclohexanone, toluene, phenol, cyclohexanol, benzeneor cyclohexane. These intermediate compounds are generally obtained frommineral oil. In view of a growing desire to prepare materials using moresustainable technology it would be desirable to provide a method whereincaprolactam is prepared from an intermediate compound that can beobtained from a biologically renewable source or at least from anintermediate compound that is converted into caprolactam using abiochemical method. Further, it would be desirable to provide a methodthat requires less energy than conventional chemical processes makinguse of bulk chemicals from petrochemical origin.

It is known to prepare caprolactam from 6-ACA, e.g. as described in U.S.Pat. No. 6,194,572. As disclosed in WO 2005/068643, 6-ACA may beprepared biochemically by converting 6-aminohex-2-enoic acid (6-AHEA) inthe presence of an enzyme having α,β-enoate reductase activity. The6-AHEA may be prepared from lysine, e.g. biochemically or by purechemical synthesis. Although the preparation of 6-ACA via the reductionof 6-AHEA is feasible by the methods disclosed in WO 2005/068643, theinventors have found that—under the reduction reaction conditions—6-AHEAmay spontaneously and substantially irreversibly cyclise to form anundesired side-product, notably β-homoproline. This cyclisation may be abottleneck in the production of 6-ACA, and may lead to a considerableloss in yield.

It is an object of the invention to provide a novel method for preparing6-ACA or caprolactam—which may, inter alia, be used for the preparationof polyamide—or an intermediate compound for the preparation of 6-ACA orcaprolactam, that can serve as an alternative for known methods.

It is a further object to provide a novel method that would overcome oneor more of the drawbacks mentioned above.

One or more further objects which may be solved in accordance with theinvention, will follow from the description, below.

It has now been found possible to prepare 6-ACA from a specific startingcompound, namely it has been found possible to prepare 6-aminocaproicacid (6-ACA), wherein the 6-aminocaproic acid is prepared from2-oxo-heptanedioic acid also known as α-ketopimelic acid (AKP). Inparticular, the preparation may be carried out in two or more reactionsteps. For instance, a method is provided wherein AKP is first convertedinto 5-formylpentanoate (5-formylvaleric acid, 5-FVA), which 5-FVA isconverted into 6-ACA. Further a method is provided wherein AKP is firstconverted into alpha-aminopimelic acid (AAP). Thereafter, AAP isconverted into 6-ACA.

The inventors realised that in principle, it is possible to prepare6-ACA from AKP in an entirely chemical (i.e. without the use of abiocatalyst) manner. Examples of suitable chemical ways of carrying outindividual reaction steps are given herein below. However, the inventorsalso realised that it is possible to prepare 6-ACA biochemically fromAKP.

Accordingly, the present invention in particular relates to a method forpreparing 6-ACA, wherein the 6-ACA is prepared from AKP, using at leastone biocatalyst.

The invention further relates to a method, wherein 6-ACA is preparedfrom 5-formylpentanoate (5-formylvaleric acid, 5-FVA), using abiocatalyst. As indicated above, the 5-FVA may be obtained from AKP.

In an embodiment, 6-ACA prepared in a method of the invention is usedfor preparing caprolactam. Such method comprises cyclising the6-amino-caproic acid, optionally in the presence of a biocatalyst.

When referring herein to carboxylic acids or carboxylates, e.g. 6-ACA,2-aminoheptanedioic acid (α-aminopimelic acid, herein after abbreviatedas ‘AAP’), another amino acid, 5-FVA or AKP, these terms are meant toinclude the protonated carboxylic acid group (i.e. the neutral group),their corresponding carboxylate (their conjugated bases) as well assalts thereof. When referring herein to amino acids, e.g. 6-ACA, thisterm is meant to include amino acids in their zwitterionic form (inwhich the amino group is in the protonated and the carboxylate group isin the deprotonated form), the amino acid in which the amino group isprotonated and the carboxylic group is in its neutral form, and theamino acid in which the amino group is in its neutral form and thecarboxylate group is in the deprotonated form, as well as salts thereof.

In accordance with the invention, no problems have been noticed withrespect to an undesired cyclisation of an intermediate product, whenforming 6-ACA and optionally caprolactam, resulting in a loss of yield.

It is envisaged that a method of the invention allows a comparable oreven better yield than the method described in WO 2005/68643. It isenvisaged that a method of the invention may in particular be favourableif a use is made of a living organism—in particular in a method whereingrowth and maintenance of the organism is taken into account.

It is further envisaged that in an embodiment of the invention theproductivity of 6-ACA (g/l.h formed) in a method of the invention may beimproved.

The term “or” as used herein is defined as “and/or” unless specifiedotherwise.

The term “a” or “an” as used herein is defined as “at least one” unlessspecified otherwise.

When referring to a noun (e.g. a compound, an additive, etc.) in thesingular, the plural is meant to be included.

When referring to a compound of which stereoisomers exist, the compoundmay be any of such stereoisomers or a combination thereof. Thus, whenreferred to, e.g., an amino acid of which enantiomers exist, the aminoacid may be the L-enantiomer, the D-enantiomer or a combination thereof.In case a natural stereoisomer exists, the compound is preferably anatural stereoisomer.

When an enzyme is mentioned with reference to an enzyme class (EC)between brackets, the enzyme class is a class wherein the enzyme isclassified or may be classified, on the basis of the Enzyme Nomenclatureprovided by the Nomenclature Committee of the International Union ofBiochemistry and Molecular Biology (NC-IUBMB), which nomenclature may befound at http://www.chem.qmul.ac.uk/iubmb/enzyme/. Other suitableenzymes that have not (yet) been classified in a specified class but maybe classified as such, are meant to be included.

The term “homologue” is used herein in particular for polynucleotides orpolypeptides having a sequence identity of at least 30%, preferably atleast 40%, more preferably at least 60%, more preferably at least 65%,more preferably at least 70%, more preferably at least 75%, morepreferably at least 80%, in particular at least 85%, more in particularat least 90%, at least 91%, at least 92%, at least 93%, at least 94%, atleast 95%, at least 96%, at least 97%, at least 98% or at least 99%. Theterm homologue is also meant to include nucleic acid sequences(polynucleotide sequences) which differ from another nucleic acidsequence due to the degeneracy of the genetic code and encode the samepolypeptide sequence.

Sequence identity or similarity is herein defined as a relationshipbetween two or more polypeptide sequences or two or more nucleic acidsequences, as determined by comparing the sequences. Usually, sequenceidentities or similarities are compared over the whole length of thesequences, but may however also be compared only for a part of thesequences aligning with each other. In the art, “identity” or“similarity” also means the degree of sequence relatedness betweenpolypeptide sequences or nucleic acid sequences, as the case may be, asdetermined by the match between such sequences. Preferred methods todetermine identity or similarity are designed to give the largest matchbetween the sequences tested. In context of this invention a preferredcomputer program method to determine identity and similarity between twosequences includes BLASTP and BLASTN (Altschul, S. F. et al., J. Mol.Biol. 1990, 215, 403-410, publicly available from NCBI and other sources(BLAST

Manual, Altschul, S., et al., NCBI NLM NIH Bethesda, Md. 20894).Preferred parameters for polypeptide sequence comparison using BLASTPare gap open 10.0, gap extend 0.5, Blosum 62 matrix. Preferredparameters for nucleic acid sequence comparison using BLASTN are gapopen 10.0, gap extend 0.5, DNA full matrix (DNA identity matrix).

In accordance with the invention, a biocatalyst is used, i.e. at leastone reaction step in the method is catalysed by a biological material ormoiety derived from a biological source, for instance an organism or abiomolecule derived there from The biocatalyst may in particularcomprise one or more enzymes. The biocatalyst may be used in any form.In an embodiment, one or more enzymes are used isolated from the naturalenvironment (isolated from the organism it has been produced in), forinstance as a solution, an emulsion, a dispersion, (a suspension of)freeze-dried cells, as a lysate, or immobilised on a support. In anembodiment, one or more enzymes form part of a living organism (such asliving whole cells).

The enzymes may perform a catalytic function inside the cell. It is alsopossible that the enzyme may be secreted into a medium, wherein thecells are present.

Living cells may be growing cells, resting or dormant cells (e.g.spores) or cells in a stationary phase. It is also possible to use anenzyme forming part of a permeabilised cell (i.e. made permeable to asubstrate for the enzyme or a precursor for a substrate for the enzymeor enzymes).

A biocatalyst used in a method of the invention may in principle be anyorganism, or be obtained or derived from any organism. The organism maybe eukaryotic or prokaryotic. In particular the organism may be selectedfrom animals (including humans), plants, bacteria, archaea, yeasts andfungi.

In an embodiment a biocatalyst originates from an animal, in particularfrom a part thereof—e.g. liver, pancreas, brain, kidney, heart or otherorgan. The animal may in particular be selected from the group ofmammals, more in particular selected from the group of Leporidae,Muridae, Suidae and Bovidae.

Suitable plants in particular include plants selected from the group ofAsplenium; Cucurbitaceae, in particular Curcurbita, e.g. Curcurbitamoschata (squash), or Cucumis; Mercurialis, e.g. Mercurialis perennis;Hydnocarpus; and Ceratonia.

Suitable bacteria may in particular be selected amongst the group ofVibrio, Pseudomonas, Bacillus, Corynebacterium, Brevibacterium,Enterococcus, Streptococcus, Klebsiella, Lactococcus, Lactobacillus,Clostridium, Escherichia, Thermus, Mycobacterium, Zymomonas, Proteus,Agrobacterium, Geobacillus, Acinetobacter, Ralstonia, Rhodobacter,Paracoccus, Novosphingobium, Nitrosomonas, Legionella, Neisseria,Rhodopseudomonas, Staphylococcus, Deinococcus and Salmonella.

Suitable archaea may in particular be selected amongst the group ofArchaeoglobus, Aeropyrum, Halobacterium, Methanosarcina, Methanococcus,Thermoplasma, Pyrobaculum, Methanocaldococcus, Methanobacterium,Methanosphaera, Methanopyrus and Methanobrevibacter.

Suitable fungi may in particular be selected amongst the group ofRhizopus, Neurospora, Penicillium and Aspergillus.

A suitable yeast may in particular be selected amongst the group ofCandida, Hansenula, Kluyveromyces and Saccharomyces.

It will be clear to the person skilled in the art that use can be madeof a naturally occurring biocatalyst (wild type) or a mutant of anaturally occurring biocatalyst with suitable activity in a methodaccording to the invention. Properties of a naturally occurringbiocatalyst may be improved by biological techniques known to theskilled person in the art, such as e.g. molecular evolution or rationaldesign. Mutants of wild-type biocatalysts can for example be made bymodifying the encoding DNA of an organism capable of acting as abiocatalyst or capable of producing a biocatalytic moiety (such as anenzyme) using mutagenesis techniques known to the person skilled in theart (random mutagenesis, site-directed mutagenesis, directed evolution,gene recombination, etc.). In particular the DNA may be modified suchthat it encodes an enzyme that differs by at least one amino acid fromthe wild-type enzyme, so that it encodes an enzyme that comprises one ormore amino acid substitutions, deletions and/or insertions compared tothe wild-type, or such that the mutants combine sequences of two or moreparent enzymes or by effecting the expression of the thus modified DNAin a suitable (host) cell. The latter may be achieved by methods knownto the skilled person in the art such as codon optimisation or codonpair optimisation, e.g. based on a method as described in WO2008/000632.

A mutant biocatalyst may have improved properties, for instance withrespect to one or more of the following aspects: selectivity towards thesubstrate, activity, stability, solvent tolerance, pH profile,temperature profile, substrate profile, susceptibility to inhibition,cofactor utilisation and substrate-affinity. Mutants with improvedproperties can be identified by applying e.g. suitable high through-putscreening or selection methods based on such methods known to theskilled person in the art.

When referred to a biocatalyst, in particular an enzyme, from aparticular source, recombinant biocatalysts, in particular enzymes,originating from a first organism, but actually produced in a(genetically modified) second organism, are specifically meant to beincluded as biocatalysts, in particular enzymes, from that firstorganism.

In a preferred method of the invention, the preparation comprises abiocatalytic (usually an enzymatic) reaction in the presence of abiocatalyst capable of catalysing the decarboxylation of an a-keto acidor an amino acid (i.e. a compound comprising at least one carboxylicacid group and at least one amino group). An enzyme having suchcatalytic activity may therefore be referred to as an α-keto aciddecarboxylase respectively an amino acid decarboxylase.

Said acid preferably is a diacid, wherein the said biocatalyst isselective towards the acid group next to the keto- or amino-group.

In general, a suitable decarboxylase has α-ketopimelate decarboxylaseactivity, capable of catalysing the conversion of AKP into 5-FVA orα-aminopimelate decarboxylase activity, capable of catalysing theconversion of AAP to 6-ACA.

An enzyme capable of decarboxylating an α-keto acid or an amino acid mayin particular be selected from the group of decarboxylases (E.C. 4.1.1),preferably from the group of oxaloacetate decarboxylases (EC 4.1.1.3),diaminopimelate decarboxylases (EC 4.1.1.20), branched chain α-keto aciddecarboxylases (EC 4.1.1.72), α-ketoisovalerate decarboxylases,α-ketoglutarate decarboxylases (EC 4.1.1.71), and pyruvatedecarboxylases (EC 4.1.1.1).

One or more other suitable decarboxylases may be selected amongst thegroup of oxalate decarboxylases (EC 4.1.1.2), acetoacetatedecarboxylases (EC 4.1.1.4), valine decarboxylases/leucinedecarboxylases (EC 4.1.1.14), glutamate decarboxylases (EC 4.1.1.15),aspartate 1-decarboxylases (EC 4.1.1.11), 3-hydroxyglutamatedecarboxylases (EC 4.1.1.16), ornithine decarboxylases (EC 4.1.1.17),lysine decarboxylases (EC 4.1.1.18), arginine decarboxylases (EC4.1.1.19), 2-oxoglutarate decarboxylases (EC 4.1.1.71), anddiaminobutyrate decarboxylases (EC 4.1.1.86)

A decarboxylase may in particular be a decarboxylase of an organismselected from the group of squashes; cucumbers; yeasts; fungi, e.g.Saccharomyces cerevisiae, Candida flareri, Hansenula sp., Kluyveromycesmarxianus, Rhizopus javanicus, and Neurospora crassa; mammals, inparticular from mammalian brain; and bacteria, such as Escherichia coli,Lactococcus lactis, Mycobacterium tuberculosis, Pseudomonas sp. andZymomonas mobilis.

The pyruvate decarboxylase may originate from Saccharomyces cerevisiaeor Zymomonas mobilis. In particular, pyruvate decarboxylase mutant 1472Afrom Zymomonas mobilis may be used.

Glutamate decarboxylase, diaminopimelate decarboxylase or aspartatedecarboxylase from Escherichia coli (E. coli) may be used.

Glutamate decarboxylase from Neurospora crassa, Mycobacterium leprae,Clostridium perfringens, Lactobacillus brevis, Mycobacteriumtuberculosis, Streptococcus or Lactococcus may be used. Examples ofLactococcus species from which the glutamate decarboxylase may originatein particular include Lactococcus lactis, such as Lactococcus lactisstrain B1157, Lactococcus lactis IFPL730, more in particular Lactococcuslactis var. maltigenes (formerly named Streptococcus lactis var.maltigenes).

An oxaloacetate decarboxylase from Pseudomonas may in particular beused.

A branched-chain alpha-keto acid decarboxylase from Lactococcus lactismay be used. More in particular, an alpha-ketoisovalerate decarboxylasefrom Lactococcus lactis may be used.

An alpha-ketoglutarate decarboxylase from Mycobacterium tuberculosis mayin particular be used.

In a preferred method of the invention, the preparation of 6-ACAcomprises an enzymatic reaction in the presence of an enzyme capable ofcatalysing a transamination reaction in the presence of an amino donor,selected from the group of aminotransferases (E.C. 2.6.1).

In general, a suitable aminotransferase has 6-aminocaproic acid6-aminotransferase activity, capable of catalysing the conversion of5-FVA into 6-ACA or α-aminopimelate 2-aminotransferase activity, capableof catalysing the conversion of AKP into AAP.

The aminotransferase may in particular be selected amongst the group ofβ-aminoisobutyrate:α-ketoglutarate aminotransferases, β-alanineaminotransferases, aspartate aminotransferases, 4-amino-butyrateaminotransferases (EC 2.6.1.19), L-lysine 6-aminotransferase (EC2.6.1.36), 2-aminoadipate aminotransferases (EC 2.6.1.39),5-aminovalerate aminotransferases (EC 2.6.1.48), 2-aminohexanoateaminotransferases (EC 2.6.1.67) and lysine:pyruvate 6-aminotransferases(EC 2.6.1.71).

In an embodiment an aminotransferase may be selected amongst the groupof alanine aminotransferases (EC 2.6.1.2), leucine aminotransferases (EC2.6.1.6), alanine-oxo-acid aminotransferases (EC 2.6.1.12),β-alanine-pyruvate aminotransferases (EC 2.6.1.18),(S)-3-amino-2-methylpropionate aminotransferases (EC 2.6.1.22),L,L-diaminopimelate aminotransferase (EC 2.6.1.83).

The aminotransferase may in particular be selected amongstaminotransferases from a mammal; Mercurialis, in particular Mercurialisperennis, more in particular shoots of Mercurialis perennis; Asplenium,more in particular Asplenium unilaterale or Asplenium septentrionale;Ceratonia, more in particular Ceratonia siliqua; Rhodobacter, inparticular Rhodobacter sphaeroides, Staphylococcus, in particularStaphylococcus aureus; Vibrio, in particular Vibrio fluvialis;Pseudomonas, in particular Pseudomonas aeruginosa; Rhodopseusomonas;Bacillus, in particular Bacillus weihenstephanensis and Bacillussubtilis; Legionella; Nitrosomas; Neisseria; or yeast, in particularSaccharomyces cerevisiae.

In case the enzyme is of a mammal, it may in particular originate frommammalian kidney, from mammalian liver, from mammalian heart or frommammalian brain. For instance a suitable enzyme may be selected amongstthe group of β-aminoisobutyrate:α-ketoglutarate aminotransferase frommammalian kidney, in particular β-aminoisobutyrate:α-ketoglutarateaminotransferase from hog kidney; β-alanine aminotransferase frommammalian liver, in particular β-alanine aminotransferase from rabbitliver; aspartate aminotransferase from mammalian heart; in particularaspartate aminotransferase from pig heart; 4-amino-butyrateaminotransferase from mammalian liver, in particular 4-amino-butyrateaminotransferase from pig liver; 4-amino-butyrate aminotransferase frommammalian brain, in particular 4-aminobutyrate aminotransferase fromhuman, pig, or rat brain; α-ketoadipate-glutamate aminotransferase fromNeurospora, in particular α-ketoadipate: glutamate aminotransferase fromNeurospora crassa; 4-amino-butyrate aminotransferase from E. coli, orα-aminoadipate aminotransferase from Thermus, in particularα-aminoadipate aminotransferase from Thermus thermophilus, and5-aminovalerate aminotransferase from Clostridium in particular fromClostridium aminovalericum. A suitable 2-aminoadipate aminotransferasemay e.g. be provided by Pyrobaculum islandicum.

In particular, the amino donor can be selected from the group ofammonia, ammonium ions, amines and amino acids. Suitable amines areprimary amines and secondary amines. The amino acid may have a D- orL-configuration. Examples of amino donors are alanine, glutamate,isopropylamine, 2-aminobutane, 2-aminoheptane, phenylmethanamine,1-phenyl-1-aminoethane, glutamine, tyrosine, phenylalanine, aspartate,β-aminoisobutyrate, β-alanine, 4-aminobutyrate, and α-aminoadipate.

In a further preferred embodiment, the method for preparing 6-ACAcomprises a biocatalytic reaction in the presence of an enzyme capableof catalysing a reductive amination reaction in the presence of anammonia source, selected from the group of oxidoreductases acting on theCH-NH₂ group of donors (EC 1.4), in particular from the group of aminoacid dehydrogenases (E.C. 1.4.1). In general, a suitable amino aciddehydrogenase has 6-aminocaproic acid 6-dehydrogenase activity,catalysing the conversion of 5-FVA into 6-ACA or has a-aminopimelate2-dehydrogenase activity, catalysing the conversion of AKP into AAP. Inparticular a suitable amino acid dehydrogenase be selected amongst thegroup of diaminopimelate dehydrogenases (EC 1.4.1.16), lysine6-dehydrogenases (EC 1.4.1.18), glutamate dehydrogenases (EC 1.4.1.3; EC1.4.1.4), and leucine dehydrogenases (EC 1.4.1.9).

In an embodiment, an amino acid dehydrogenase may be selected amongst anamino acid dehydrogenases classified as glutamate dehydrogenases actingwith NAD or NADP as acceptor (EC 1.4.1.3), glutamate dehydrogenasesacting with NADP as acceptor (EC 1.4.1.4), leucine dehydrogenases (EC1.4.1.9), diaminopimelate dehydrogenases (EC 1.4.1.16), and lysine6-dehydrogenases (EC 1.4.1.18).

An amino acid dehydrogenase may in particular originate from an organismselected from the group of Corynebacterium, in particularCorynebacterium glutamicum; Proteus, in particular Proteus vulgaris;Agrobacterium, in particular Agrobacterium tumefaciens; Geobacillus, inparticular Geobacillus stearothermophilus; Acinetobacter, in particularAcinetobacter sp. ADP1;Ralstonia, in particular Ralstonia solanacearum;Salmonella, in particular Salmonella typhimurium; Saccharomyces, inparticular Saccharomyces cerevisiae; Brevibacterium, in particularBrevibacterium flavum; and Bacillus, in particular Bacillus sphaericus,Bacillus cereus or Bacillus subtilis. For instance a suitable amino aciddehydrogenase may be selected amongst diaminopimelate dehydrogenasesfrom Bacillus, in particular Bacillus sphaericus; diaminopimelatedehydrogenases from Brevibacterium sp.; diaminopimelate dehydrogenasesfrom Corynebacterium, in particular diaminopimelate dehydrogenases fromCorynebacterium glutamicum; diaminopimelate dehydrogenases from Proteus,in particular diaminopimelate dehydrogenase from Proteus vulgaris;lysine 6-dehydrogenases from Agrobacterium, in particular Agrobacteriumtumefaciens, lysine 6-dehydrogenases from Geobacillus, in particularfrom Geobacillus stearothermophilus; glutamate dehydrogenases actingwith NADH or NADPH as cofactor (EC 1.4.1.3) from Acinetobacter, inparticular glutamate dehydrogenases from Acinetobacter sp. ADP1;glutamate dehydrogenases (EC 1.4.1.3) from Ralstonia, in particularglutamate dehydrogenases from Ralstonia solanacearum; glutamatedehydrogenases acting with NADPH as cofactor (EC 1.4.1.4) fromSalmonella, in particular glutamate dehydrogenases from Salmonellatyphimurium; glutamate dehydrogenases (EC 1.4.1.4) from Saccharomyces,in particular glutamate dehydrogenases from Saccharomyces cerevisiae;glutamate dehydrogenases (EC 1.4.1.4) from Brevibacterium, in particularglutamate dehydrogenases from Brevibacterium flavum; and leucinedehydrogenases from Bacillus, in particular leucine dehydrogenases fromBacillus cereus or Bacillus subtilis.

In a specific embodiment, AKP is biocatalytically converted into5-formylpentanoate (5-FVA) in the presence of a decarboxylase or otherbiocatalyst catalysing such conversion. A decarboxylase used inaccordance with the invention may in particular be selected from thegroup of α-keto acid decarboxylases from Lactococcus lactis, Lactococcuslactis var. maltigenes or Lactococcus lactis subsp. cremoris; branchedchain α-keto acid decarboxylases from Lactococcus lactis strain B1157 orLactococcus lactis IFPL730; pyruvate decarboxylases from Saccharomycescerevisiae, Candida flareri, Zymomonas mobilis, Hansenula sp., Rhizopusjavanicus, Neurospora crassa, or Kluyveromyces marxianus;α-ketoglutarate decarboxylases from Mycobacterium tuberculosis;glutamate decarboxylases from E. coli, Lactobacillus brevis,Mycobacterium leprae, Neurospora crassa or Clostridium perfringens; andaspartate decarboxylases from E. coli.

In particular, a decarboxylase from Escherichia coli, Zymomonas mobilis,Saccharomyces cerevisiae, Mycobacterium tuberculosis, Pseudomonasspecies, or Lactococcus lactis has been found suitable to catalyse theconversion of AKP into 5-FVA. More in particular, a biocatalystcomprising a decarboxylase having a amino acid sequence as identified bySequence ID 31, Sequence ID 34, Sequence ID 37, Sequence ID 40, SequenceID 43, Sequence ID 46 or a homologue thereof may be used. It is alsoenvisaged that such decarboxylase may be used to prepare 6-ACA from AAP.

Thereafter 5-FVA is converted into 6-ACA. This can be done chemically:6-ACA can be prepared in high yield by reductive amination of 5-FVA withammonia over a hydrogenation catalyst, for example Ni on SiO₂/Al₂O₃support, as described for 9-aminononanoic acid (9-aminopelargonic acid)and 12-aminododecanoic acid (12-aminolauric acid) in EP-A 628 535 or DE4 322 065.

Alternatively, 6-ACA can be obtained by hydrogenation over PtO₂ of6-oximocaproic acid, prepared by reaction of 5-FVA and hydroxylamine.(see e.g. F. O. Ayorinde, E. Y. Nana, P. D. Nicely, A. S. Woods, E. O.Price, C. P. Nwaonicha J. Am. Oil Chem. Soc. 1997, 74, 531-538 forsynthesis of the homologous 12-aminododecanoic acid).

In an embodiment, the conversion of 5-FVA to 6-ACA is performedbiocatalytically in the presence of (i) an amino donor and (ii) anaminotransferase, an amino acid dehydrogenase or another biocatalystcapable of catalysing such conversion. In particular in such anembodiment the aminotransferase may be selected from the group ofaminotransferases from Vibrio fluvialis, Pseudomonas aeruginosa,Bacillus subtilis, Bacillus weihenstephanensis or Escherichia coli;β-aminoisobutyrate:α-ketoglutarate aminotransferase from hog kidney;β-alanine aminotransferase from rabbit liver; aminotransferase fromshoots from Mercurialis perennis; 4-aminobutyrate aminotransferase frompig liver or from human, rat, or pig brain; β-alanine aminotransferasefrom rabbit liver; and L-lysine:α-ketoglutarate-ε-aminotransferase. Incase an amino acid dehydrogenase is used, such amino acid dehydrogenasemay in particular be selected from the group of lysine 6-dehydrogenasesfrom Agrobacterium tumefaciens or Geobacillus stearothermophilus.Another suitable amino acid dehydrogenase may be selected from the groupof diaminopimelate dehydrogenases from Bacillus sphaericus,Brevibacterium sp., Corynebacterium glutamicum, or Proteus vulgaris;from the group of glutamate dehydrogenases acting with NADH or NADPH ascofactor (EC 1.4.1.3) from Acinetobacter sp. ADP1 or Ralstoniasolanacearum; from the group of glutamate dehydrogenases acting withNADPH as cofactor (EC 1.4.1.4) from Salmonella typhimurium; from thegroup of glutamate dehydrogenases (EC 1.4.1.4) from Saccharomycescerevisiae or Brevibacterium flavum; or from the group of leucinedehydrogenases from Bacillus cereus or Bacillus subtilis.

In a specific embodiment, the conversion of 5-FVA to 6-ACA is catalysedby a biocatalyst comprising an aminotransferase comprising an amino acidsequence according to Sequence ID 2, Sequence ID 5, Sequence ID 8,Sequence ID 65, Sequence ID 67, Sequence ID 69 or a homologue of any ofthese sequences.

In a specific embodiment, AKP is chemically converted into 5-FVA.Efficient chemical decarboxylation of a 2-keto carboxylic acid into thecorresponding aldehyde can be performed by intermediate enamineformation using a secondary amine, for instance morpholine, underazeotropic water removal and simultaneous loss of CO₂, e.g. based on amethod as described in Tetrahedron Lett. 1982, 23(4), 459-462. Theintermediate terminal enamide is subsequently hydrolysed to thecorresponding aldehyde. 5-FVA may thereafter be biocatalyticallyconverted into 6-ACA by transamination in the presence of anaminotransferase or by enzymatic reductive amination by an amino aciddehydrogenase or another biocatalyst able of catalysing such conversion.Such aminotransferase or amino acid dehydrogenase may in particular beselected from the biocatalysts mentioned above when describing theconversion of 5-FVA to 6-ACA.

Alternatively, the conversion of 5-FVA to 6-ACA may be performed by achemical method, e.g. as mentioned above.

In a specific embodiment, AKP is biocatalytically converted into AAP inthe presence of (i) an aminotransferase, an amino acid dehydrogenase, oranother biocatalyst capable of catalysing such conversion and (ii) anamino donor. Such aminotransferase used in accordance with the inventionfor the conversion of AKP to AAP may in particular be selected fromaminotransferases mentioned above, more in particular from the group ofaspartate aminotransferases from pig heart; α-ketoadipate:glutamateaminotransferases from Neurospora crassa or yeast; aminotransferasesfrom shoots from Mercurialis perennis; 4-aminobutyrate aminotransferasesfrom E. coli; α-aminoadipate aminotransferases from Thermusthermophilus; aminotransferases from Asplenium septentrionale orAsplenium unilaterale; and aminotransferases from Ceratonia siliqua.

In a preferred embodiment, the aminotransferase for the conversion ofAKP to AAP is selected from the group of aminotransferases from Vibrio,Pseudomonas, Bacillus, Legionella, Nitrosomonas, Neisseria, Rhodobacter,Escherichia and Rhodopseudomonas.

In particular, aminotransferases from an organism selected from thegroup of Bacillus subtilis, Rhodobacter sphaeroides, Legionellapneumophila, Nitrosomonas europaea, Neisseria gonorrhoeae, Pseudomonassyringae, Rhodopseudomonas palustris, Vibrio fluvialis, Escherichia coliand Pseudomonas aeruginosa, have been found suitable to catalyse theconversion of AKP to AAP.

In a specific embodiment, for the conversion of AKP to AAP anaminotransferase is used comprising an amino acid sequence according toSequence ID 2, Sequence ID 8, Sequence ID 12, Sequence ID 15, SequenceID 17, Sequence ID 19, Sequence ID 21, Sequence ID 23, Sequence ID 25,Sequence ID 27, Sequence ID 29 or a homologue of any of these sequences.

In a further embodiment, the method for preparing AAP comprises abiocatalytic reaction in the presence of an enzyme capable of catalysinga reductive amination reaction in the presence of an ammonia source,selected from the group of oxidoreductases acting on the CH—NH₂ group ofdonors (EC 1.4), in particular from the group of amino aciddehydrogenases (E.C. 1.4.1). In general, a suitable amino aciddehydrogenase has α-aminopimelate 2-dehydrogenase activity, catalysingthe conversion of AKP into AAP.

In particular a suitable amino acid dehydrogenase may be selected fromthe group of diaminopimelate dehydrogenases (EC 1.4.1.16), glutamatedehydrogenases (EC 1.4.1.3; EC 1.4.1.4), and leucine dehydrogenases (EC1.4.1.9).

In an embodiment, an amino acid dehydrogenase is selected amongst aminoacid dehydrogenases classified as glutamate dehydrogenases acting withNAD or NADP as acceptor (EC 1.4.1.3), glutamate dehydrogenases actingwith NADP as acceptor (EC 1.4.1.4), leucine dehydrogenases (EC 1.4.1.9),and diaminopimelate dehydrogenases (EC 1.4.1.16).

An amino acid dehydrogenase may in particular originate from an organismselected from the group of Corynebacterium, in particularCorynebacterium glutamicum; Proteus, in particular Proteus vulgaris;Agrobacterium, in particular Agrobacterium tumefaciens; Geobacillus, inparticular Geobacillus stearothermophilus; Acinetobacter, in particularAcinetobacter sp. ADP1; Ralstonia, in particular Ralstonia solanacearum;Salmonella, in particular Salmonella typhimurium; Saccharomyces, inparticular Saccharomyces cerevisiae; Brevibacterium, in particularBrevibacterium flavum; and Bacillus, in particular Bacillus sphaericus,Bacillus cereus or Bacillus subtilis.

For instance a suitable amino acid dehydrogenase may be selected amongstdiaminopimelate dehydrogenases from Bacillus, in particular Bacillussphaericus; diaminopimelate dehydrogenases from Brevibacterium sp.;diaminopimelate dehydrogenases from Corynebacterium, in particulardiaminopimelate dehydrogenases from Corynebacterium glutamicum;diaminopimelate dehydrogenases from Proteus, in particulardiaminopimelate dehydrogenase from Proteus vulgaris; glutamatedehydrogenases acting with NADH or NADPH as cofactor (EC 1.4.1.3) fromAcinetobacter, in particular glutamate dehydrogenases from Acinetobactersp. ADP1; glutamate dehydrogenases (EC 1.4.1.3) from Ralstonia, inparticular glutamate dehydrogenases from Ralstonia solanacearum;glutamate dehydrogenases acting with NADPH as cofactor (EC 1.4.1.4) fromSalmonella, in particular glutamate dehydrogenases from Salmonellatyphimurium; glutamate dehydrogenases (EC 1.4.1.4) from Saccharomyces,in particular glutamate dehydrogenases from Saccharomyces cerevisiae;glutamate dehydrogenases (EC 1.4.1.4) from Brevibacterium, in particularglutamate dehydrogenases from Brevibacterium flavum; and leucinedehydrogenases from Bacillus, in particular leucine dehydrogenases fromBacillus cereus or Bacillus subtilis.

Another suitable amino acid dehydrogenase may be selected from the groupof lysine 6-dehydrogenases from Agrobacterium tumefaciens or Geobacillusstearothermophilus; or from the group of leucine dehydrogenases fromBacillus cereus or Bacillus subtilis.

AAP prepared in a method of the invention may further be used for thepreparation of 6-ACA. The inventors have realised that AAP, preparedfrom AKP, can be converted into 6-ACA by a decarboxylation reaction.This can be performed chemically, for instance by heating in a highboiling solvent in the presence of a ketone or aldehyde catalyst. Forexample, amino acids are decarboxylated in good yields in cyclohexanolat 150-160° C. with 1-2 v/v % of cyclohexenone as described by M.Hashimoto, Y. Eda, Y. Osanai, T. Iwai and S. Aoki in Chem. Lett. 1986,893-896. Similar methods are described in Eur. Pat. Appl. 1586553, 2005by Daiso, and by S. D. Brandt, D. Mansell, S. Freeman, I. A. Fleet, J.F. Alder J. Pharm. Biomed. Anal. 2006, 41, 872-882.

Alternatively, the decarboxylation of AAP to 6-ACA may be performedbiocatalytically in the presence of a decarboxylase or other biocatalystcatalysing such decarboxylation.

The decarboxylase may be selected amongst decarboxylases capable ofcatalysing the decarboxylation of an α-amino acid. An enzyme capable ofdecarboxylating an alpha-amino acid may in particular be selected fromthe group of decarboxylases (E.C. 4.1.1), preferably from the group ofpyruvate decarboxylases (EC 4.1.1.1), diaminopimelate decarboxylases (EC4.1.1.20), diaminopimelate decarboxylases (EC 4.1.1.20), branched chainalpha-keto acid decarboxylases (EC 4.1.1.72), which includealpha-ketoisovalerate decarboxylases, and alpha-ketoglutaratedecarboxylases (EC 4.1.1.71).

One or more other suitable decarboxylases may in particular be selectedamongst the group of oxalate decarboxylases (EC 4.1.1.2), oxaloacetatedecarboxylases (EC 4.1.1.3), acetoacetate decarboxylases (EC 4.1.1.4),aspartate 1-decarboxylases (EC 4.1.1.11), valine decarboxylases/leucinedecarboxylases (EC 4.1.1.14), glutamate decarboxylases (EC 4.1.1.15),3-hydroxyglutamate decarboxylases (EC 4.1.1.16), ornithinedecarboxylases (EC 4.1.1.17), lysine decarboxylases (EC 4.1.1.18),arginine decarboxylases (EC 4.1.1.19), 2-oxoglutarate decarboxylases (EC4.1.1.71), and diaminobutyrate decarboxylases (EC 4.1.1.86).

A decarboxylase may in particular be a decarboxylase of an organismselected from the group of squashes, e.g. Curcurbita moschata;cucumbers; yeasts; fungi, e.g. Saccharomyces cerevisiae, Candidaflareri, Hansenula sp., Kluyveromyces marxianus, Rhizopus javanicus, andNeurospora crassa; mammals, in particular from mammalian brain; andbacteria such as Escherichia coli, Lactococcus lactis, Mycobacteriumtuberculosis, Pseudomonas sp. and Zymomonas mobilis.

The pyruvate decarboxylase may originate from Saccharomyces cerevisiaeor Zymomonas mobilis. In particular, pyruvate decarboxylase mutant 1472Afrom Zymomonas mobilis may be used. An oxaloacetate decarboxylase fromPseudomonas may in particular be used. Glutamate decarboxylase oraspartate decarboxylase from Escherichia coli (E. coli) may be used, orglutamate decarboxylase from Neurospora crassa, Mycobacterium leprae,Clostridium perfringens, Lactobacillus brevis, Mycobacteriumtuberculosis, Streptococcus or Lactococcus may be used. Examples ofLactococcus species from which the glutamate decarboxylase may originatein particular include Lactococcus lactis, such as Lactococcus lactisstrain B1157, Lactococcus lactis IFPL730, more in particular Lactococcuslactis var. maltigenes (formerly named Streptococcus lactis var.maltigenes). A diaminopimelate decarboxylase may, e.g., be from anorganism capable of synthesising lysine from diaminopimelate. Suchorganism may in particular be found amongst bacteria, archaea andplants. In particular, the diaminopimelate decarboxylase may be from agram negative bacterium, for instance E. coli. Branched-chain alpha-ketoacid decarboxylases from Lactococcus lactis may be used. More inparticular, branched chain alpha-keto acid decarboxylases andalpha-ketoisovalerate decarboxylases from Lactococcus lactis may beused.

An alpha-ketoglutarate decarboxylase from Mycobacterium tuberculosis mayin particular be used. The inventors have found that alpha-ketoglutaratedecarboxylase (Kgd) from Mycobacterium tuberculosis may be used forconverting AAP into 6-ACA. In particular, the inventors have found thatsuch decarboxylase comprising a sequence as shown in SEQUENCE ID No. 46or a functional analogue thereof may be capable of catalysing theformation of 6-ACA from AAP.

A glutamate decarboxylase may in particular be selected from Curcurbitamoschata, cucumber, yeast, or calf brain; and diaminopimelatedecarboxylases (EC 4.1.1.20).

A diaminopimelate decarboxylase may, e.g., be from an organism capableof synthesising lysine from diaminopimelate. Such organism may inparticular be found amongst bacteria, archaea and plants.

In particular, the diaminopimelate decarboxylase may be from a gramnegative bacterium, for instance E. coli.

In a specific embodiment, AKP is chemically converted into AAP. AAP canbe prepared from 2-oxopimelic acid by catalytic Leuckart-Wallachreaction as described for similar compounds. This reaction is performedwith ammonium formate in methanol and [RhCp*Cl₂]₂ as homogeneouscatalyst (M. Kitamura, D. Lee, S. Hayashi, S. Tanaka, M. Yoshimura J.Org. Chem. 2002, 67, 8685-8687). Alternatively, the Leuckart-Wallachreaction can be performed with aqueous ammonium formate using[Ir^(III)Cp*(bpy)H₂O]SO₄ as catalyst as described by S. Ogo, K. Ueharaand S. Fukuzumi in J. Am. Chem. Soc. 2004, 126, 3020-3021.Transformation of α-keto acids into (enantiomerically enriched) aminoacids is also possible by reaction with (chiral) benzylamines andsubsequent hydrogenation of the intermediate imine over Pd/C orPd(OH)₂/C. See for example, R. G. Hiskey, R. C. Northrop J. Am. Chem.Soc. 1961, 83, 4798.

Thereafter AAP is biocatalytically converted into 6-ACA, in the presenceof a decarboxylase or another biocatalyst capable of performing suchdecarboxylation. Such decarboxylase may in particular be selectedamongst the biocatalysts referred to above, when describing biocatalystsfor the conversion of AAP to 6-ACA.

Alternatively, the conversion of AAP to 6-ACA may be performed by achemical method, e.g. as mentioned above.

In a specific embodiment, AKP is biocatalytically converted into 5-FVAin the presence of a decarboxylase or other biocatalyst capable ofcatalysing such conversion and 5-FVA is thereafter converted into 6-ACAin the presence of an aminotransferase, amino acid dehydrogenase, orother biocatalyst capable of catalysing such conversion. Decarboxylasessuitable for these reactions may in particular be selected from thegroup of decarboxylases mentioned above, when describing thebiocatalytic conversion of AKP into 5-FVA. A suitable aminotransferaseor amino acid dehydrogenase for the conversion of 5-FVA may inparticular be selected from those mentioned above, when describing thebiocatalytic conversion of 5-FVA to 6-ACA.

In a specific embodiment, AKP is biocatalytically converted into AAP inthe presence of an aminotransferase, amino acid dehydrogenase, or otherbiocatalyst capable of catalysing such conversion and AAP is thereafterconverted into 6-ACA in the presence of a decarboxylase or otherbiocatalyst capable of catalysing such conversion.

Enzymes suitable for these reactions may in particular be selected fromthe group of aminotransferases, amino acid dehydrogenases, anddecarboxylases which have been described above when describing thebiocatalytic conversion of AKP into AAP and the biocatalytic conversionof AAP into 6-ACA respectively.

AKP used to prepare 6-ACA may in principle be obtained in any way. Forinstance, AKP may be obtained based on a method as described by H. Jägeret al. Chem. Ber. 1959, 92, 2492-2499. AKP can be prepared by alkylatingcyclopentanone with diethyl oxalate using sodium ethoxide as a base,refluxing the resultant product in a strong acid (2 M HCl) andrecovering the product, e.g. by crystallisation from toluene. It is alsopossible to obtain AKP from a natural source, e.g. from methanogenicArchaea, from Asplenium septentrionale, or from Hydnocarpusanthelminthica. AKP may for instance be extracted from such organism, ora part thereof, e.g. from Hydnocarpus anthelminthica seeds. A suitableextraction method may e.g. be based on the method described in A. I.Virtanen and A. M. Berg in Acta Chemica Scandinavica 1954, 6,1085-1086,wherein the extraction of amino acids and AKP from Asplenium, using 70%ethanol, is described.

In a specific embodiment, AKP is prepared in a method comprisingconverting alpha-ketoglutaric acid (AKG) into alpha-ketoadipic acid(AKA) and converting alpha-ketoadipic acid into alpha-ketopimelic acid.This reaction may be catalysed by a biocatalyst. AKG may, e.g., beprepared biocatalytically from a carbon source, such as a carbohydrate,in a manner known in the art per se.

A suitable biocatalyst for preparing AKP from AKG may in particular beselected amongst biocatalysts catalysing C₁-elongation ofalpha-ketoglutaric acid into alpha-ketoadipic acid and/or C₁-elongationof alpha-ketoadipic acid into alpha-ketopimelic acid.

In a specific embodiment, the preparation of AKP is catalysed by abiocatalyst comprising

a. an AksA enzyme or an homologue thereof;

b. at least one enzyme selected from the group of AksD enzymes, AksEenzymes, homologues of AksD enzymes and homologues of AksE enzymes; and

c. an AksF enzyme or a homologue thereof.

One or more of the AksA, AksD, AksE, AksF enzymes or homologues thereofmay be found in an organism selected from the group of methanogenicarchaea, preferably selected from the group of Methanococcus,Methanocaldococcus, Methanosarcina, Methanothermobacter, Methanosphaera,Methanopyrus and Methanobrevibacter.

In a specific embodiment, the biocatalyst catalysing the preparation ofAKP from alpha-ketoglutaric acid (AKG) comprises an enzyme systemcatalysing the conversion of alpha-ketoglutaric acid intoalpha-ketoadipic acid, wherein said enzyme system forms part of thealpha-amino adipate pathway for lysine biosynthesis. The term ‘enzymesystem’ is in particular used herein for a single enzyme or a group ofenzymes whereby a specific conversion can be catalysed.

The preparation of AKP from AKG may comprise one or more biocatalyticreactions with known or unknown intermediates e.g. the conversion of AKGinto AKA or the conversion of AKA into AKP. Such system may be presentinside a cell or isolated from a cell. The enzyme system may inparticular be from an organism selected from the group of yeasts, fungi,archaea and bacteria, in particular from the group of Penicillium,Cephalosporium, Paelicomyces, Trichophytum, Aspergillus, Phanerochaete,Emericella, Ustilago, Schizosaccharomyces, Saccharomyces, Candida,Yarrowia, Pichia, Kluyveromyces, Thermus, Deinococcus, Pyrococcus,Sulfolobus, Thermococcus, Methanococcus, Methanocaldococcus,Methanosphaera, Methanopyrus, Methanobrevibacter, Methanosarcina andMethanothermobacter.

In a specific embodiment, the biocatalyst catalysing the preparation ofAKP from alpha-ketoglutaric acid comprises an enzyme system catalysingthe conversion of alpha-ketoglutaric acid into alpha-ketoadipic acid,wherein at least one of the enzymes of the enzyme system originates fromnitrogen fixing bacteria selected from the group of cyanobacteria,rhizobiales, γ-proteobacteria and actinobacteria, in particular from thegroup of Anabaena, Microcystis, Synechocystis, Rhizobium,Bradyrhizobium, Pseudomonas, Azotobacter, Klebsiella and Frankia.

Examples of homologues for these Aks enzymes and the genes encodingthese enzymes are given in the Tables 1A and 1B on the following pages.

TABLE 1A Enzyme name Organism gene Protein AksA Methanocaldococcusjannashii MJ0503 NP_247479 Methanothermobacter thermoautotropicum ΔHMTH1630 NP_276742 Methanococcus maripaludis S2 MMP0153 NP_987273Methanococcus maripaludis C5 MmarC5_1522 YP_001098033 Methanococcusmaripaludis C7 MmarC7_1153 YP_001330370 Methanosphaera stadtmanae DSM3091 Msp_0199 YP_447259 Methanopyrus kandleri AV19 MK1209 NP_614492Methanobrevibacter smithii ATCC35061 Msm_0722 YP_001273295 Methanococcusvannielii SB Mevan_1158 YP_001323668 Methanococcus aeolicus Nankai 3Maeo_0994 YP_001325184 AksD Methanocaldococcus jannashii MJ1003NP_247997 Methanothermobacter thermoautotropicum ΔH MTH1386 NP_276502Methanococcus maripaludis S2 Mmp1480 NP_988600 Methanococcus maripaludisC5 MmarC5_0098 YP_001096630 Methanococcus maripaludis C7 MmarC7_0724YP_001329942 Methanosphaera stadtmanae DSM 3091 Msp_1486 YP_448499Methanopyrus kandleri AV19 MK1440 NP_614723 Methanobrevibacter smithiiATCC35061 Msm_0723 YP_001273296 Methanococcus vannielii SB Mevan_0789YP_001323307 Methanococcus aeolicus Nankai 3 Maeo_0311 YP_001324511References to gene and protein can be found via www.ncbi.nlm.nih.gov/,(as available on 15 Apr. 2008)

TABLE 1B Enzyme name Orgamism gene Protein AksE Methanocaldococcusjannashii MJ1271 NP_248267 Methanothermobacter thermoautotropicum ΔHMTH1387 NP_276503 Methanococcus maripaludis S2 MMP0381 NP_987501Methanococcus maripaludis C5 MmarC5_1257 YP_001097769 Methanococcusmaripaludis C7 MmarC7_1379 YP_001330593 Methanosphaera stadtmanae DSM3091 Msp_1485 YP_448498 Methanopyrus kandleri AV19 MK0781 NP_614065Methanobrevibacter smithii ATCC35061 Msm_0847 YP_001273420 Methanococcusvannielii SB Mevan_1368 YP_001323877 Methanococcus aeolicus Nankai 3Maeo_0652 YP_001324848 AksF Methanocaldococcus jannashii MJ1596NP_248605 Methanothermobacter thermoautotropicum ΔH MTH184 NP_275327Methanococcus maripaludis S2 MMP0880 NP988000 Methanococcus maripaludisC5 MmarC5_0688 YP001097214 Methanococcus maripaludis C7 MmarC7_0128YP_001329349 Methanosphaera stadtmanae DSM 3091 Msp_0674 YP_447715Methanopyrus kandleri AV19 MK0782 NP_614066 Methanobrevibacter smithiiATCC35061 Msm_0373 YP001272946 Methanococcus vannielii SB Mevan_0040YP_001322567 Methanococcus aeolicus Nankai 3 Maeo_1484 YP_001325672References to gene and protein can be found via www.ncbi.nlm.nih.gov/,(as available on 15 Apr. 2008)

If desired, 6-ACA obtained in accordance with the invention can becyclised to form caprolactam, e.g. as described in U.S. Pat. No.6,194,572.

Reaction conditions for any biocatalytic step in the context of thepresent invention may be chosen depending upon known conditions for thebiocatalyst, in particular the enzyme, the information disclosed hereinand optionally some routine experimentation.

In principle, the pH of the reaction medium used may be chosen withinwide limits, as long as the biocatalyst is active under the pHconditions. Alkaline, neutral or acidic conditions may be used,depending on the biocatalyst and other factors. In case the methodincludes the use of a micro-organism, e.g. for expressing an enzymecatalysing a method of the invention, the pH is selected such that themicro-organism is capable of performing its intended function orfunctions. The pH may in particular be chosen within the range of fourpH units below neutral pH and two pH units above neutral pH, i.e.between pH 3 and pH 9 in case of an essentially aqueous system at 25° C.A system is considered aqueous if water is the only solvent or thepredominant solvent (>50 wt. %, in particular >90 wt. %, based on totalliquids), wherein e.g. a minor amount of alcohol or another solvent (<50wt. %, in particular <10 wt. %, based on total liquids) may be dissolved(e.g. as a carbon source) in such a concentration that micro-organismswhich may be present remain active. In particular in case a yeast and/ora fungus is used, acidic conditions may be preferred, in particular thepH may be in the range of pH 3 to pH 8, based on an essentially aqueoussystem at 25° C. If desired, the pH may be adjusted using an acid and/ora base or buffered with a suitable combination of an acid and a base.

In principle, the incubation conditions can be chosen within wide limitsas long as the biocatalyst shows sufficient activity and/or growth. Thisincludes aerobic, micro-aerobic, oxygen limited and anaerobicconditions.

Anaerobic conditions are herein defined as conditions without any oxygenor in which substantially no oxygen is consumed by the biocatalyst, inparticular a micro-organism, and usually corresponds to an oxygenconsumption of less than 5 mmol/l.h, in particular to an oxygenconsumption of less than 2.5 mmol/l.h, or less than 1 mmol/l.h.

Aerobic conditions are conditions in which a sufficient level of oxygenfor unrestricted growth is dissolved in the medium, able to support arate of oxygen consumption of at least 10 mmol/l.h, more preferably morethan 20 mmol/l.h, even more preferably more than 50 mmol/l.h, and mostpreferably more than 100 mmol/l.h.

Oxygen-limited conditions are defined as conditions in which the oxygenconsumption is limited by the oxygen transfer from the gas to theliquid. The lower limit for oxygen-limited conditions is determined bythe upper limit for anaerobic conditions, i.e. usually at least 1mmol/l.h, and in particular at least 2.5 mmol/l.h, or at least 5mmol/l.h. The upper limit for oxygen-limited conditions is determined bythe lower limit for aerobic conditions, i.e. less than 100 mmol/l.h,less than 50 mmol/l.h, less than 20 mmol/l.h, or less than to 10mmol/l.h.

Whether conditions are aerobic, anaerobic or oxygen limited is dependenton the conditions under which the method is carried out, in particularby the amount and composition of ingoing gas flow, the actualmixing/mass transfer properties of the equipment used, the type ofmicro-organism used and the micro-organism density.

In principle, the temperature used is not critical, as long as thebiocatalyst, in particular the enzyme, shows substantial activity.Generally, the temperature may be at least 0° C., in particular at least15° C., more in particular at least 20° C. A desired maximum temperaturedepends upon the biocatalyst. In general such maximum temperature isknown in the art, e.g. indicated in a product data sheet in case of acommercially available biocatalyst, or can be determined routinely basedon common general knowledge and the information disclosed herein. Thetemperature is usually 90° C. or less, preferably 70° C. or less, inparticular 50° C. or less, more in particular or 40° C. or less.

In particular if a biocatalytic reaction is performed outside a hostorganism, a reaction medium comprising an organic solvent may be used ina high concentration (e.g. more than 50%, or more than 90 wt. %), incase an enzyme is used that retains sufficient activity in such amedium.

In an advantageous method 6-ACA is prepared making use of a whole cellbiotransformation of the substrate for 6-ACA or an intermediate forforming 6-ACA (AKP, AAP or 5-FVA), comprising a micro-organism whereinone or more biocatalysts (usually one or more enzymes) catalysing thebiotransformation are produced, such as one or more biocatalystsselected from the group of biocatalysts capable of catalysing theconversion of AKP to AAP, biocatalysts capable of catalysing theconversion of AAP to 6-ACA, biocatalysts capable of catalysing theconversion of AKP to 5-FVA and biocatalysts capable of catalysing theconversion of 5-FVA to 6-ACA. In a preferred embodiment themicro-organism is capable of producing a decarboxylase and/or at leastone enzyme selected from amino acid dehydrogenases and aminotransferasesare produced. capable of catalysing a reaction step as described above,and a carbon source for the micro-organism.

The carbon source may in particular contain at least one compoundselected from the group of monohydric alcohols, polyhydric alcohols,carboxylic acids, carbon dioxide, fatty acids, glycerides, includingmixtures comprising any of said compounds. Suitable monohydric alcoholsinclude methanol and ethanol, Suitable polyols include glycerol andcarbohydrates. Suitable fatty acids or glycerides may in particular beprovided in the form of an edible oil, preferably of plant origin.

In particular a carbohydrate may be used, because usually carbohydratescan be obtained in large amounts from a biologically renewable source,such as an agricultural product, preferably an agriculturalwaste-material. Preferably a carbohydrate is used selected from thegroup of glucose, fructose, sucrose, lactose, saccharose, starch,cellulose and hemi-cellulose. Particularly preferred are glucose,oligosaccharides comprising glucose and polysaccharides comprisingglucose.

A cell, in particular a recombinant cell, comprising one or morebiocatalysts (usually one or more enzymes) for catalysing a reactionstep in a method of the invention can be constructed using molecularbiological techniques, which are known in the art per se. For instance,if one or more biocatalysts are to be produced in a recombinant cell(which may be a heterologous system), such techniques can be used toprovide a vector (such as a recombinant vector) which comprises one ormore genes encoding one or more of said biocatalysts. One or morevectors may be used, each comprising one or more of such genes. Suchvector can comprise one or more regulatory elements, e.g. one or morepromoters, which may be operably linked to a gene encoding anbiocatalyst.

As used herein, the term “operably linked” refers to a linkage ofpolynucleotide elements (or coding sequences or nucleic acid sequence)in a functional relationship. A nucleic acid sequence is “operablylinked” when it is placed into a functional relationship with anothernucleic acid sequence. For instance, a promoter or enhancer is operablylinked to a coding sequence if it affects the transcription of thecoding sequence.

As used herein, the term “promoter” refers to a nucleic acid fragmentthat functions to control the transcription of one or more genes,located upstream with respect to the direction of transcription of thetranscription initiation site of the gene, and is structurallyidentified by the presence of a binding site for DNA-dependent RNApolymerase, transcription initiation sites and any other DNA sequences,including, but not limited to transcription factor binding sites,repressor and activator protein binding sites, and any other sequencesof nucleotides known to one of skilled in the art to act directly orindirectly to regulate the amount of transcription from the promoter. A“constitutive” promoter is a promoter that is active under mostenvironmental and developmental conditions. An “inducible” promoter is apromoter that is active under environmental or developmental regulation.The term “homologous” when used to indicate the relation between a given(recombinant) nucleic acid or polypeptide molecule and a given hostorganism or host cell, is understood to mean that in nature the nucleicacid or polypeptide molecule is produced by a host cell or organisms ofthe same species, preferably of the same variety or strain.

The promoter that could be used to achieve the expression of the nucleicacid sequences coding for an enzyme for use in a method of theinvention, in particular an aminotransferase, an amino aciddehydrogenase or a decarboxylase, such as described herein above may benative to the nucleic acid sequence coding for the enzyme to beexpressed, or may be heterologous to the nucleic acid sequence (codingsequence) to which it is operably linked. Preferably, the promoter ishomologous, i.e. endogenous to the host cell.

If a heterologous promoter (to the nucleic acid sequence encoding forthe enzyme of interest) is used, the heterologous promoter is preferablycapable of producing a higher steady state level of the transcriptcomprising the coding sequence (or is capable of producing moretranscript molecules, i.e. mRNA molecules, per unit of time) than is thepromoter that is native to the coding sequence. Suitable promoters inthis context include both constitutive and inducible natural promotersas well as engineered promoters, which are well known to the personskilled in the art.

A “strong constitutive promoter” is one which causes mRNAs to beinitiated at high frequency compared to a native host cell. Examples ofsuch strong constitutive promoters in Gram-positive micro-organismsinclude SP01-26, SP01-15, veg, pyc (pyruvate carboxylase promoter), andamyE.

Examples of inducible promoters in Gram-positive micro-organismsinclude, the IPTG inducible Pspac promoter, the xylose inducible PxyIApromoter.

Examples of constitutive and inducible promoters in Gram-negativemicroorganisms include, but are not limited to, tac, tet, trp-tet, lpp,lac, lpp-lac, laclq, T7, T5, T3, gal, trc, ara (P_(BAD)), SP6, λ-P_(R),and λ-P_(L).

Promoters for (filamentous) fungal cells are known in the art and canbe, for example, the glucose-6-phosphate dehydrogenase gpdA promoters,protease promoters such as pepA, pepB, pepC, the glucoamylase glaApromoters, amylase amyA, amyB promoters, the catalase catR or catApromoters, glucose oxidase goxC promoter, beta-galactosidase lacApromoter, alpha-glucosidase aglA promoter, translation elongation factortefA promoter, xylanase promoters such as xlnA, xlnB, xlnC, xlnD,cellulase promoters such as eg/A, eg/B, cbhA, promoters oftranscriptional regulators such as areA, creA, xlnR, pacC, prfT, oranother promotor, and can be found among others at the NCBI website(http://www.ncbi.nlm.nih.gov/entrez/).

The term “heterologous” when used with respect to a nucleic acid (DNA orRNA) or protein refers to a nucleic acid or protein that does not occurnaturally as part of the organism, cell, genome or DNA or RNA sequencein which it is present, or that is found in a cell or location orlocations in the genome or DNA or RNA sequence that differ from that inwhich it is found in nature. Heterologous nucleic acids or proteins arenot endogenous to the cell into which it is introduced, but has beenobtained from another cell or synthetically or recombinantly produced.Generally, though not necessarily, such nucleic acids encode proteinsthat are not normally produced by the cell in which the DNA istranscribed or expressed. Similarly exogenous RNA encodes for proteinsnot normally expressed in the cell in which the exogenous RNA ispresent. Heterologous nucleic acids and proteins may also be referred toas foreign nucleic acids or proteins. Any nucleic acid or protein thatone of skill in the art would recognize as heterologous or foreign tothe cell in which it is expressed is herein encompassed by the termheterologous nucleic acid or protein.

A method according to the invention may be carried out in a hostorganism, which may be novel.

Accordingly, the invention also relates to a host cell comprising one ormore biocatalysts capable of catalysing at least one reaction step in amethod of the invention, in particular capable of catalysing at leastone reaction step in the conversion of AKP, AAP or 5-FVA to 6-ACA. Theinvention also relates to a novel vector comprising one or more genesencoding for one or more enzymes capable of catalysing at least onereaction step in a method of the invention, in particular capable ofcatalysing at least one reaction step in the conversion of AKP to 6-ACAand to a novel host cell comprising one or more genes encoding for oneor more enzymes capable of catalysing at least one reaction step in amethod of the invention, in particular capable of catalysing at leastone reaction step in the conversion of AKP to 6-ACA (which one or moregenes may form part of one or more vectors).

In a specific embodiment, a host cell according to the invention is arecombinant cell comprising a nucleic acid sequence encoding abiocatalyst capable of catalysing a transamination reaction or areductive amination reaction to form alpha-aminopimelic acid fromalpha-ketopimelic acid. Said sequence may be part of a vector or mayhave been inserted into the chromosomal DNA.

In particular, a host cell or vector according to the invention maycomprise at least one nucleic acid sequence, in particular at least twonucleic acid sequences, selected from the group of nucleic acidsequences encoding an enzyme with α-ketopimelic acid decarboxylaseactivity, nucleic acid sequences encoding an enzyme with5-formylpentanoate aminotransferase activity, nucleic acid sequencesencoding an enzyme with α-ketopimelic acid aminotransferase activity,nucleic acid sequences encoding an enzyme with α-ketopimelic aciddehydrogenase activity and nucleic acid sequences encoding an enzymewith α-aminopimelic acid decarboxylase activity. Of these sequences,typically one or more, in particular two or more, are recombinantsequences.

In preferred embodiment the host cell, typically a recombinant hostcell, or the vector according to the invention comprises a nucleic acidsequence encoding at least one biocatalyst having α-ketopimelic aciddecarboxylase activity, and/or at least one nucleic acid sequenceselected from sequences encoding a biocatalyst with 5-formylpentanoateaminotransferase activity.

In such an embodiment, the nucleic acid sequence encoding an enzyme withα-ketopimelic acid decarboxylase activity may in particular comprise anamino acid sequence according to Sequence ID 31, Sequence ID 34,Sequence ID 37, Sequence ID 40, Sequence ID 43 or Sequence ID 46 or ahomologue of any of these sequences and/or the nucleic acid sequenceencoding an enzyme with 5-formylpentanoate aminotransferase may inparticular comprise an amino acid sequence according to Sequence ID 2,Sequence ID 5, Sequence ID 8, Sequence ID 65 Sequence ID 67, Sequence ID69 or a homologue thereof. One or more of said nucleic acid sequencesmay form part of one or more recombinant vectors.

In a further preferred embodiment, the vector or host cell comprises anucleic acid sequence encoding an enzyme with α-ketopimelic acidaminotransferase activity and/or a nucleic acid sequence encoding anenzyme with α-aminopimelic acid decarboxylase activity. The nucleic acidsequence encoding an enzyme with α-ketopimelic acid aminotransferaseactivity may in particular comprise an amino acid sequence according toSequence ID 2, Sequence ID 8, Sequence ID 12, Sequence ID 15, SequenceID 17, Sequence ID 19, Sequence ID 21, Sequence ID 23, Sequence ID 25,Sequence ID 27, Sequence ID 29, or a homologue thereof. One or more ofsaid nucleic acid sequences may form part of one or more recombinantvectors.

In a specific preferred embodiment, a host cell according to theinvention comprises a nucleic acid sequence encoding an enzyme withα-aminopimelate 2-dehydrogenase activity and a nucleic acid sequenceencoding an enzyme with α-aminopimelate decarboxylase activity.

In a specific preferred embodiment, a host cell according to theinvention comprises a nucleic acid sequence encoding an enzyme with6-aminocaproic acid 6- dehydrogenase activity and a nucleic acidsequence encoding an enzyme with α-ketopimelic acid decarboxylaseactivity.

One or more suitable genes of a host cell or vectors according to theinvention may in particular be selected amongst genes encoding an enzymeas mentioned herein above.

In a specific embodiment, the host cell is a recombinant cell comprisingat least one nucleic acid sequence selected from the group of sequencesas identified in any of Sequence ID 1, Sequence ID 3, Sequence ID 4,Sequence ID 6, Sequence ID 7, Sequence ID 11, Sequence ID 13, SequenceID 14, Sequence ID 16, Sequence ID 18, Sequence ID 20, Sequence ID 22,Sequence ID 24, Sequence ID 26, Sequence ID 28, Sequence ID 30, SequenceID 32, Sequence ID 33, Sequence ID 35, Sequence ID 36, Sequence ID 38,Sequence ID 39, Sequence ID 41, Sequence ID 42, Sequence ID 44, SequenceID 45, Sequence ID 47, Sequence ID 64, Sequence ID 66, Sequence ID 68and functional analogues thereof.

A nucleic acid sequence encoding an enzyme with 5-FVA aminotransferaseactivity, may in particular be a sequence selected from the group ofsequences represented by any of the Sequence ID's 1, 3, 4, 6, 7, 64, 66,68, and functional analogues of any of these sequences.

As used herein, the term “functional analogues” at least includes othersequences encoding an enzyme having the same amino acid sequence andother sequences encoding a homologue of such enzyme.

A nucleic acid sequence encoding an enzyme with AKP decarboxylaseactivity may in particular be a sequence selected from the group ofsequences represented by any of the Sequence ID's 30, 32, 33, 35, 36,38, 39, 41, 42, 44, 45, 47 and functional analogues of any of thesesequences.

In a preferred embodiment, the host cell comprises a nucleic acidsequence encoding an enzyme, capable of catalysing the conversion of AAPto AKP, according to Sequence ID No.: 1, 3, 7, 11, 13, 14, 16, 18, 20,22, 24, 26, 28, or a functional analogue thereof, which may be a wildtype or non-wild type sequence

In a specific embodiment, the host cell comprises at least one nucleicacid sequence encoding a biocatalyst having alpha-aminopimelic aciddecarboxylase activity, which may be homologous or heterologous to thehost cell. In particular such biocatalyst may be selected from the groupof decarboxylases (E.C. 4.1.1), more in particular from the group ofglutamate decarboxylases (EC 4.1.1.15), diaminopimelate decarboxylases(EC 4.1.1.20) aspartate 1-decarboxylases (EC 4.1.1.11), branched chainalpha-keto acid decarboxylases, alpha-ketoisovalerate decarboxylases,alpha-ketoglutarate decarboxylases, pyruvate decarboxylases (EC 4.1.1.1)and oxaloacetate decarboxylases (E.C. 4.1.1.3).

In a specific embodiment, the host cell comprises one or more enzymescatalysing the formation of AKP from AKG (see also above). Use may bemade of an enzyme system forming part of the alpha-amino adipate pathwayfor lysine biosynthesis. The term ‘enzyme system’ is in particular usedherein for a single enzyme or a group of enzymes whereby a specificconversion can be catalysed. Said conversion may comprise one or morechemical reactions with known or unknown intermediates e.g. theconversion of AKG into AKA or the conversion of AKA into AKP. Suchsystem may be present inside a cell or isolated from a cell. It is knownthat aminotransferases often have a wide substrate range. If present, itmay be desired to decrease activity of one or more such enzymes in ahost cell such that activity in the conversion of AKA toalpha-aminoadipate (AAA) is reduced, whilst maintaining relevantcatalytic functions for biosynthesis of other amino acids or cellularcomponents. Also a host cell devoid of any other enzymatic activityresulting in the conversion of AKA to an undesired side product ispreferred.

In a preferred host cell, suitable for preparing AAP making use of awhole cell biotransformation process, one or more biocatalysts capableof catalysing at least one reaction step in the preparation ofalpha-ketopimelic acid from alpha-ketoglutaric acid are encoded for.Suitable biocatalysts are, e.g., as described above when discussing thepreparation of AKP.

The host cell may for instance be selected from bacteria, yeasts orfungi. In particular the host cell may be selected from the generaselected from the group of Aspergillus, Penicillium, Saccharomyces,Kluyveromyces, Pichia, Candida, Hansenula, Bacillus, Corynebacterium,Pseudomonas, Gluconobacter, Methanococcus, Methanobacterium,Methanocaldococcus and Methanosarcina and Escherichia. Herein, usuallyone or more encoding nucleic acid sequences as mentioned above have beencloned and expressed.

In particular, the host strain and, thus, a host cell suitable for thebiochemical synthesis of 6-ACA may be selected from the group ofEscherichia coli, Bacillus subtilis, Bacillus amyloliquefaciens,Corynebacterium glutamicum, Aspergillus niger, Penicillium chrysogenum,Saccharomyces cervisiae, Hansenula polymorpha, Candida albicans,Kluyveromyces lactis, Pichia stipitis, Pichia pastoris, Methanobacteriumthermoautothrophicum ΔH, Methanococcus maripaludis, Methanococcusvoltae, Methanosarcina acetivorans, Methanosarcina barkeri andMethanosarcina mazei host cells. In a preferred embodiment, the hostcell is capable of producing lysine (as a precursor).

The host cell may be in principle a naturally occurring organism or maybe an engineered organism. Such an organism can be engineered using amutation screening or metabolic engineering strategies known in the art.In a specific embodiment, the host cell naturally comprises (or iscapable of producing) one or more of the enzymes suitable for catalysinga reaction step in a method of the invention, such as one or moreactivities selected from the group of decarboxylases, aminotransferasesand amino acid dehydrogenases capable of catalysing a reaction step in amethod of the invention. For instance E. coli may naturally be capableof producing an enzyme catalysing a transamination in a method of theinvention. It is also possible to provide a recombinant host cell withboth a recombinant gene encoding an aminotransferase or amino aciddehydrogenase capable of catalysing a reaction step in a method of theinvention and a recombinant gene encoding a decarboxylase gene capableof catalysing a reaction step in a method of the invention.

For instance a host cell may be selected of the genus Corynebacterium,in particular C. glutamicum, enteric bacteria, in particular Escherichiacoli, Bacillus, in particular B. subtilis and B. methanolicus, andSaccharomyces, in particular S. cerevisiae. Particularly suitable are C.glutamicum or B. methanolicus strains which have been developed for theindustrial production of lysine.

The invention further relates to a micro-organism, which may be awild-type micro-organism isolated from its natural environment or arecombinant micro-organism, comprising DNA containing a nucleic acidsequence as identified in any Sequence ID selected from the group ofSequence ID 3, Sequence ID 6, Sequence ID 13, Sequence ID No. 32,Sequence ID No. 35, Sequence ID No. 41, Sequence ID No. 44, Sequence IDNo. 47, and functional analogues thereof.

Functional analogues of a nucleotides sequence, as referred to herein,are in particular nucleotide sequences encoding the same amino acidsequence as that nucleotide sequence or encoding a homologue of thatnucleotide sequence. In particular, preferred functional analogues arenucleotide sequence having a similar, the same or a better level ofexpression in a host cell of interest as the nucleotide sequence ofwhich it is referred to as being a functional analogue of.

The invention further relates to a polynucleotide or vector comprising anucleic acid sequence as identified in any Sequence ID selected from thegroup of Sequence ID 3, Sequence ID 6, Sequence ID 13, Sequence ID No.32, Sequence ID No. 35, Sequence ID No. 41, Sequence ID No. 44, SequenceID No. 47 and non-wild-type functional analogues thereof. Suchpolynucleotide or vector is in particular advantageous for providing ahost cell, especially an E. coli host cell, or another host cell whichis capable of catalysing at least one reaction step in the conversion ofAKP to 6-ACA with a high yield, compared to a corresponding wild-typegene.

Optionally, the polynucleotide or vector comprises one or more nucleicacid sequences encoding one or more other biocatalysts suitable forcatalysing a reaction step in a method according to the invention, inparticular such one or more of the biocatalyst referred to above.

The invention further relates to a method for preparingalpha-aminopimelic acid (AAP), comprising converting AKP into AAP, whichconversion is catalysed by a biocatalyst.

For such method in particular a biocatalyst may be used havingaminotransferase activity or reductive amination activity as describedabove.

As indicated above, the AAP may thereafter be used for the preparationof 6-ACA. Alternatively, AAP may be used as such, e.g. as a chemical forbiochemical research or as a pH-buffer compound, e.g. for use in anpreparative or analytical separation technique such as liquidchromatography or capillary electrophoresis.

Further, AAP prepared in a method of the invention may further be usedin the preparation of another compound, for instance, AAP may beconverted into caprolactam. As described above, and illustrated in anexample, below. AAP can be chemically converted in caprolactam, e.g. byexposure to a high temperature. Without being bound by theory, it iscontemplated that also in this reaction 6-ACA may be formed as ashort-lived intermediate.

Next, the invention will be illustrated by the following examples.

EXAMPLES General Methods Molecular and Genetic Techniques

Standard genetic and molecular biology techniques are generally known inthe art and have been previously described (Maniatis et al. 1982“Molecular cloning: a laboratory manual”. Cold Spring Harbor Laboratory,Cold Spring Harbor, N.Y.; Miller 1972 “Experiments in moleculargenetics”, Cold Spring Harbor Laboratory, Cold Spring Harbor; Sambrookand Russell 2001 “Molecular cloning: a laboratory manual” (3rd edition),Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press; F.Ausubel et al, eds., “Current protocols in molecular biology”, GreenPublishing and Wley Interscience, New York 1987).

Plasmids and Strains

pBAD/Myc-His C was obtained from Invitrogen (Carlsbad, Calif., USA).Plasmid pBAD/Myc-His-DEST constructed as described in WO2005/068643, wasused for protein expression. E. coli TOP10 (Invitrogen, Carlsbad,Calif., USA) was used for all cloning procedures and for expression oftarget genes.

Media

LB medium (10 g/l tryptone, 5 g/l yeast extract, 5 g/l NaCl) was usedfor growth of E. coli. Antibiotics (50 μg/ml carbenicillin) weresupplemented to maintain plasmids. For induction of gene expressionunder control of the P_(BAD) promoter in pBAD/Myc-His-DEST derivedplasmids, L-arabinose was added to a final concentration of 0.2% (w/v).

Identification of Plasmids

Plasmids carrying the different genes were identified by genetic,biochemical, and/or phenotypic means generally known in the art, such asresistance of transformants to antibiotics, PCR diagnostic analysis oftransformant or purification of plasmid DNA, restriction analysis of thepurified plasmid DNA or DNA sequence analysis.

HPLC-MS Analysis Method for the Determination of 5-FVA

5-FVA was detected by selective reaction monitoring (SRM)-MS, measuringthe transition m/z 129→83. Concentrations for 5-FVA were calculated bymeasuring the peak area of the 5-FVA peak eluting at approximately 6min. Calibration was performed by using an external standard procedure.All the LC-MS experiments were performed on an Agilent 1200 LC system,consisting of a quaternary pump, autosampler and column oven, coupledwith an Agilent 6410 QQQ triple quadrupole MS.

LC conditions: Column: 50 × 4.6 mm Nucleosil C18, 5 μm (Machery & Nagel)pre column coupled to a 250 × 4.6 mm id. Prevail C18, 5 μm (Alltech)Column room temperature temperature: Eluent: A: water containing 0.1%formic acid B: acetonitrile containing 0.1% formic acid Gradient: time(min) % eluent B 0 10 6 50 6.1 10 11 10 Flow: 1.2 ml/min, beforeentering the MS the flow is split 1:3 Injection volume: 2 μl MSconditions: Ionisation: negative ion electrospray source conditions:ionspray voltage: 5 kV temperature: 350° C. fragmentor voltage andcollision energy optimized Scan mode: selective reaction mode:transition m/z 129 → 83

HPLC-MS Analysis for the Determination of AAP

AAP was detected by selected ion monitoring (SIM)-MS, measuring theprotonated molecule for AAP with m/z 176. Concentrations for AAP werecalculated by measuring the peak area of the AAP peak eluting at aretention time of 2.7 minutes in the samples. Calibration was performedby using an external standard procedure. All the LC-MS experiments wereperformed on an Agilent 1100 LC system consisting of a quaternary pump,degasser, autosampler and column oven, coupled with an API 2000 triplequadrupole MS (Applied Biosystems).

LC conditions were as follows:

-   Column: 50*4 Nucleosil C18, 5 μm (Macherey-Nagel)+250×4.6 Prevail    C18, 5 μm (Alltech), both at room temperature (RT)-   Eluent: A=0.1% (v/v) formic acid in ultrapure water

B=0.1% (v/v) formic acid in acetonitrile (pa, Merck)

-   Flow: 1.2 ml/min, before entering the MS the flow was split 1:3-   Gradient: The gradient was started at t=0 minutes with 90% (v/v) A    and changed within 6 minutes to 50% (v/v) A. At 6.1 minutes the    gradient was changed to the original condition.-   Injection volume: 2 μl-   MS conditions: Positive ion electrospray was used for ionization-   Detection: in SIM mode on m/z 176, with a dwell time of 100 msec.

HPLC-MS Analysis for the Determination of 6-ACA

Calibration:

The calibration was performed by an external calibration line of 6-ACA(m/z 132→m/z 114, Rt 7.5 min). All the LC-MS experiments were performedon an Agilent 1100, equipped with a quaternary pump, degasser,autosampler, column oven, and a single-quadrupole MS (Agilent,Waldbronn, Germany). The LC-MS conditions were:

-   Column: 50*4 Nucleosil (Mancherey-Nagel)+250×4.6 Prevail C18    (Alltech), both at room temperature (RT)-   Eluent: A=0.1(v/v) formic acid in ultrapure water

B=Acetonitrile (pa, Merck)

-   Flow: 1.0 ml/min, before entering the MS the flow was split 1:3

Gradient: The gradient was started at t=0 minutes with 100% (v/v) A,remaining for 15 minutes and changed within 15 minutes to 80% (v/v) B(t=30 minutes). From 30 to 31 minutes the gradient was kept at constantat 80% (v/v) B.

-   Injection volume: 5 μl-   MS detection: ESI(+)-MS

The electrospray ionization (ESI) was run in the positive scan mode withthe following conditions; m/z 50-500, 50 V fragmentor, 0.1 m/z stepsize, 350° C. drying gas temperature, 10 L N₂/min drying gas, 50 psignebuliser pressure and 2.5 kV capillary voltage.

Cloning of Target Genes Design of Expression Constructs

attB sites were added to all genes upstream of the ribosomal bindingsite and start codon and downstream of the stop codon to facilitatecloning using the

Gateway technology (Invitrogen, Carlsbad, Calif., USA).

Gene Synthesis and Construction of Plasmids

Synthetic genes were obtained from DNA2.0 and codon optimised forexpression in E. coli according to standard procedures of DNA2.0. Theaminotransferase genes from Vibrio fluvialis JS17 [SEQ ID No. 1] andBacillus weihenstephanensis KBAB4 [SEQ ID No. 4] encoding the amino acidsequences of the V. fluvialis JS17 ω-aminotransferase [SEQ ID No. 2] andthe B. weihenstephanensis KBAB4 aminotransferase (ZP_01186960) [SEQ IDNo. 5], respectively, were codon optimised and the resulting sequences[SEQ ID No. 3] and [SEQ ID No. 6] were obtained by DNA synthesis.

The decarboxylase genes from Escherichia coli [SEQ ID No. 30],Saccharomyces cerevisiae [SEQ ID No. 33], Zymomonas mobilis [SEQ ID No.36], Lactococcus lactis [SEQ ID No. 39], [SEQ ID No. 42], andMycobacterium tuberculosis [SEQ ID No. 45] encoding the amino acidsequences of the V. fluvialis JS17 ω-aminotransferase [SEQ ID No. 3],the B. weihenstephanensis KBAB4 aminotransferase (ZP_01186960) [SEQ IDNo. 6], the Escherichia coli diaminopimelate decarboxylase LysA [SEQ IDNo. 31], the Saccharomyces cerevisiae pyruvate decarboxylase Pdc [SEQ IDNo. 34], the Zymomonas mobilis pyruvate decarboxylase Pdc1472A [SEQ IDNo. 37], the Lactococcus lactis branched chain alpha-keto aciddecarboxylase KdcA [SEQ ID No. 40] and alpha-ketoisovaleratedecarboxylase KivD [SEQ ID No. 43], and the Mycobacterium tuberculosisalpha-ketoglutarate decarboxylase Kgd [SEQ ID No. 46], respectively,were also codon optimised and the resulting sequences [SEQ ID No. 32],[SEQ ID No. 35], [SEQ ID No. 38], [SEQ ID No. 41], [SEQ ID No. 44], and[SEQ ID No. 47] were obtained by DNA synthesis, respectively.

The gene constructs were cloned into pBAD/Myc-His-DEST expressionvectors using the Gateway technology (Invitrogen) via the introducedattB sites and pDONR201 (Invitrogen) as entry vector as described in themanufacturer's protocols (www.invitrogen.com). This way the expressionvectors pBAD-Vfl_AT and pBAD-Bwe_AT were obtained, respectively. Thecorresponding expression strains were obtained by transformation ofchemically competent E. coli TOP10 (Invitrogen) with the respectivepBAD-expression vectors.

Cloning by PCR

Various genes encoding a biocatalyst were amplified from genomic DNA byPCR using PCR Supermix High Fidelity (Invitrogen) according to themanufacturer's specifications, using primers as listed in the followingtable.

TABLE 2 gene enzyme primer origin of gene Sequence ID Sequence IDSequence ID's Pseudomonas 7 8  9&10 aeruginosa Pseudomonas 26 27 60&61aeruginosa Pseudomonas 66 67 72&73 aeruginosa Pseudomonas 68 69 74&75aeruginosa Bacillus subtilis 14 15 48&49 Bacillus subtilis 16 17 50&51Bacillus subtilis 64 65 70&71 Rhodobacter 18 19 52&53 sphaeroidesLegionella 20 21 54&55 pneumophilia Nitrosomas europaea 22 23 56&57Neisseria 24 25 58&59 gonorrhoeae Rhodopseudomonas 28 29 62&63 palustris

PCR reactions were analysed by agarose gel electrophoresis and PCRproducts of the correct size were eluted from the gel using the QlAquickPCR purification kit (Qiagen, Hilden, Germany). Purified PCR productswere cloned into pBAD/Myc-His-DEST expression vectors using the Gatewaytechnology (Invitrogen) via the introduced attB sites and pDONR-zeo(Invitrogen) as entry vector as described in the manufacturer'sprotocols. The sequence of genes cloned by PCR was verified by DNAsequencing. This way the expression vectors pBAD-Pae-_gi9946143_AT,pBAD-Bsu_gi16078032_AT, pBAD-Bsu_gi16080075_AT, pBAD-Bsu_gi16077991_AT,pBAD-Rsp_AT, pBAD-Lpn_AT, pBAD-Neu_AT, pBAD-Ngo_AT,pBAD-Pae_gi9951299_AT, pBAD-Pae_gi9951072_AT, pBAD-Pae_gi9951630_AT andpBAD-Rpa_AT were obtained. The corresponding expression strains wereobtained by transformation of chemically competent E. coli TOP10(Invitrogen) with the pBAD constructs.

Growth of E. coli for Protein Expression

Small scale growth was carried out in 96-deep-well plates with 940 μlmedia containing 0.02% (w/v) L-arabinose. Inoculation was performed bytransferring cells from frozen stock cultures with a 96-well stamp(Kühner, Birsfelden, Switzerland). Plates were incubated on an orbitalshaker (300 rpm, 5 cm amplitude) at 25° C. for 48 h. Typically anOD_(620nm) of 2-4 was reached.

Preparation of Cell Lysates Preparation of Lysis Buffer

The lysis buffer contained the following ingredients:

TABLE 3 1M MOPS pH 7.5 5 ml DNAse I grade II (Roche) 10 mg Lysozyme 200mg MgSO_(4•)7H₂O 123.2 mg dithiothreitol (DTT) 154.2 mg H₂O (MilliQ)Balance to 100 ml

The solution was freshly prepared directly before use.

Preparation of Cell Free Extract by Lysis

Cells from small scales growth (see previous paragraph) were harvestedby centrifugation and the supernatant was discarded. The cell pelletsformed during centrifugation were frozen at −20° C. for at least 16 hand then thawed on ice. 500 μl of freshly prepared lysis buffer wereadded to each well and cells were resuspended by vigorously vortexingthe plate for 2-5 min. To achieve lysis, the plate was incubated at roomtemperature for 30 min. To remove cell debris, the plate was centrifugedat 4° C. and 6000 g for 20 min. The supernatant was transferred to afresh plate and kept on ice until further use.

Preparation of Cell Free Extract by Sonification

Cells from medium scales growth (see previous paragraph) were harvestedby centrifugation and the supernatant was discarded. 1 ml of potassiumphosphate buffer pH7 was added to 0.5 g of wet cell pellet and cellswere resuspended by vigorously vortexing. To achieve lysis, the cellswere sonicated for 20 min. To remove cell debris, the lysates werecentrifuged at ° C. and 6000 g for 20 min. The supernatant wastransferred to a fresh tube and frozen at −20° C. until further use.

Preparation of 5-Formylpentanoic Acid by Chemical Hydrolysis of Methyl5-Formylpentanoate

The substrate for the aminotransferase reaction i.e. 5-formylpentanoicacid was prepared by chemical hydrolysis of methyl 5-formylpentanoate asfollows: a 10% (w/v) solution of methyl 5-formylpentanoate in water wasset at pH 14.1 with NaOH. After 24 h of incubation at 20° C. the pH wasset to 7.1 with HCl.

Enzymatic Reactions for Conversion of 5-Formylpentanoic Acid to 6-ACA

Unless specified otherwise, a reaction mixture was prepared comprising10 mM 5-formylpentanoic acid, 20 mM racemic a-methylbenzylamine, and 200μM□ pyridoxal 5′-phosphate in 50 mM potassium phosphate buffer, pH 7.0.100 μl of the reaction mixture were dispensed into each well of the wellplates. To start the reaction, 20 μl of the cell free extracts wereadded, to each of the wells. Reaction mixtures were incubated on ashaker at 37° C. for 24 h. Furthermore, a chemical blank mixture(without cell free extract) and a biological blank (E. coli TOP10 withpBAD/Myc-His C) were incubated under the same conditions. Samples wereanalysed by HPLC-MS. The results are summarised in the following table.

TABLE 4 6-ACA formation from 5-FVA in the presence of aminotransferases6-ACA concentration Biocatalyst [mg/kg] E. coli TOP10/pBAD-Vfl_AT 43* E.coli TOP10/pBAD-Pae_AT 930  E. coli TOP10/pBAD-Pae_AT 25* E. coliTOP10/pBAD-Bwe_AT 24* E. coli TOP10/pBAD-Bsu_gi16077991_AT 288  E. coliTOP10/pBAD-Pae_gi9951072_AT 1087   E. coli TOP10/pBAD-Pae_gi9951630_AT92  E. coli TOP10 with pBAD/Myc-His C   0.6 (biological blank) None(chemical blank) n.d. n.d.: not detectable *method differed in that 10μl cell free extract was used instead of 20 μl, thepyridoxal-5′-phosphate concentration was 50 μM instead of 200 μM and thereaction mixture volume in the wells was 190 μl instead of 100 μl.

It is shown that 6-ACA is formed from 5-FVA in the presence of anaminotransferase.

Enzymatic Reactions for Conversion of AKP to 5-Formylpentanoic Acid

A reaction mixture was prepared comprising 50 mM AKP, 5 mM magnesiumchloride, 100 μM□ pyridoxal 5′-phosphate (for LysA) or 1 mM thiaminediphosphate (for all other enzymes) in 100 mM potassium phosphatebuffer, pH 6.5. 4 ml of the reaction mixture were dispensed into areaction vessel. To start the reaction, 1 ml of the cell free extractsobtained by sonification were added, to each of the wells. In case ofthe commercial oxaloacetate decarboxylase (Sigma-Aldrich product number04878), 50 U were used. Reaction mixtures were incubated with a magneticstirrer at 37° C. for 48 h. Furthermore, a chemical blank mixture(without cell free extract) and a biological blank (E. coli TOP10 withpBAD/Myc-His C) were incubated under the same conditions. Samples fromdifferent time points during the reaction were analysed by HPLC-MS. Theresults are summarised in the following table.

TABLE 5 5-FVA formation from AKP in the presence of decarboxylases 5-FVAconcentration [mg/kg] Biocatalyst 3 h 18 h 48 h E. coli TOP10/pBAD-LysA150 590 720 E. coli TOP10/pBAD-Pdc 1600 1700 1300 E. coliTOP10/pBAD-Pdcl472A 2000 2000 1600 E. coli TOP10/pBAD-KdcA 3300 23002200 E. coli TOP10/pBAD-KivD 820 1400 1500 Oxaloacetate decarboxylasen.d. 6 10 E. coli TOP10 with pBAD/Myc- n.d. n.d. n.d. His C (biologicalblank) None (chemical blank) n.d. n.d. n.d. n.d.: not detectable

It is shown that 5-FVA is formed from AKP in the presence of adecarboxylase.

Enzymatic Reactions for Conversion of AKP to 6-ACA in Presence ofRecombinant Decarboxylase

A reaction mixture was prepared comprising 50 mM AKP, 5 mM magnesiumchloride, 100 μM□ pyridoxal 5′-phosphate (for LysA) or 1 mM thiaminediphosphate (for all other tested biocatalysts) in 100 mM potassiumphosphate buffer, pH 6.5. 4 ml of the reaction mixture were dispensedinto a reaction vessel. To start the reaction, 1 ml of the cell freeextracts were added, to each of the wells. Reaction mixtures wereincubated with a magnetic stirrer at 37° C. for 48 h. Furthermore, achemical blank mixture (without cell free extract) and a biologicalblank (E. coli TOP10 with pBAD/Myc-His C) were incubated under the sameconditions. Samples from different time points during the reaction wereanalysed by HPLC-MS. The results are summarised in the following table.

TABLE 6 6-ACA formation from AKP in the presence of decarboxylases 6-ACAconcentration [mg/kg] Biocatalyst 3 h 18 h 48 h E. coli TOP10/pBAD-LysAn.a. 0.01 0   E. coli TOP10/pBAD-Pdc 0.1  0.3 n.a. E. coliTOP10/pBAD-Pdcl472A 0.03 0.1 0.2 E. coli TOP10/pBAD-KdcA 0.04 0.1 0.3 E.coli TOP10/pBAD-KivD n.a. 0.3 0.6 E. coli TOP10 with pBAD/Myc- n.d. n.d.n.d. His C (biological blank) None (chemical blank) n.d. n.d. n.d. n.a.= not analysed n.d. = not detectable

It is shown that 6-ACA is formed from AKP in the presence of adecarboxylase. It is contemplated that the E. coli contained natural5-FVA aminotransferase activity.

Enzymatic Reactions for Conversion of AKP to 6-ACA in Presence ofRecombinant Decarboxylase and Recombinant Aminotransferase

A reaction mixture was prepared comprising 50 mM AKP, 5 mM magnesiumchloride, 100 μM□ pyridoxal 5′-phosphate, 1 mM thiamine diphosphate and50 mM racemic α-methylbenzylamine in 100 mM potassium phosphate buffer,pH 6.5. 1.6 ml of the reaction mixture were dispensed into a reactionvessel. To start the reaction, 0.2 ml of the decarboxylase containingcell free extract and 0.2 ml of the aminotransferase containing cellfree extract were added, to each of the reaction vessels. Reactionmixtures were incubated with a magnetic stirrer at 37° C. for 48 h.Furthermore, a chemical blank mixture (without cell free extract) and abiological blank (E. coli TOP10 with pBAD/Myc-His C) were incubatedunder the same conditions. Samples from different time points during thereaction were analysed by HPLC-MS. The results are summarised in thefollowing table.

TABLE 7 6-ACA formation from AKP in the presence of a recombinantdecarboxylase and a recombinant aminotransferase 6-ACA concentration[mg/kg] after 48 hours AT E. coli TOP10/ E. coli TOP10/ E. coli TOP10/DC pBAD-Vfl-AT pBAD-Bwe-AT pBAD-PAE_gi9946143_AT E. coli TOP10/pBAD-Pdc183.4 248.9 117.9 E. coli TOP10/pBAD-Pdcl472A 458.5 471.6 170.3 E. coliTOP10/pBAD-KdcA 497.8 497.8 275.1 E. coli TOP10/pBAD-KivD 510.9 510.9314.4 AT = aminotransferase DC = decarboxylase

In the chemical blank and in the biological blank no 6-ACA wasdetectable.

Further, the results show that compared to the example wherein ahost-cell with only recombinant decarboxylase (and no recombinantaminotransferase) the conversion to 6-ACA was improved.

Construction of Plasmids for Expression of Aminotransferases andDecarboxylases in S. cerevisiae

The aminotransferase gene from Vibrio fluvialis JS17 encoding the aminoacid sequence of the V. fluvialis JS17 ω-aminotransferase [SEQ ID No. 2]was amplified by PCR from pBAD-Vfl_AT [SEQ ID No. 3] using Phusion DNApolymerase (Finnzymes) according to the manufacturers specifications andusing specific primers [SEQ ID No. 76 & 77].

The aminotransferase gene from Pseudomonas aeruginosa [SEQ ID No. 7]coding for P. aeruginosa aminotransferase [SEQ ID No. 8] was amplifiedfrom pBAD-Pae_AT by PCR using Phusion DNA polymerase (Finnzymes)according to the manufacturers specifications and using specific primers[SEQ ID No. 78 & 79].

The resulting PCR products were cloned into vector pAKP-41 using SpeIand BamHI restriction enzymes resulting in vectors pAKP-79 and pAKP-80respectively, which now contain the aminotransferase gene under the S.cerevisiae gal10 promoter and the S. cerevisiae adh2 terminator.

The decarboxylase gene from Saccharamyces cerevisiae [SEQ ID No. 33]coding for Saccharamyces cerevisiae pyruvate decarboxylase Pdc [SEQ IDNo. 34] was amplified from pBAD-Pdc by PCR using Phusion DNA polymerase(Finnzymes) according to the manufacturers specifications and usingspecific primers [SEQ ID No 80 & 81].

The decarboxylase gene from Lactococcus lactis [SEQ ID No. 39] codingfor Lactococcus lactis branched chain alpha-keto acid decarboxylase KdcA[SEQ ID No. 40] was amplified from pBAD-KdcA by PCR using Phusion DNApolymerase (Finnzymes) according to the manufacturers specifications andusing specific primers [SEQ ID No 82 & 83].

The resulting PCR products were cloned into vector pAKP-44 using AscIand BamHI restriction enzymes resulting in vectors pAKP-81 and pAKP-82respectively, which now contain the decarboxylase gene under the S.cerevisiae gal2 promoter and the S. cerevisiae pma1 terminator.

Plasmids pAKP-79 and pAKP-80 were restriction enzyme digested with SacIand XbaI and plasmids pAKP-81 and pAKP-82 were restriction enzymedigested with SalI and XbaI. A SacI/XbaI aminotransferase fragment wascombined with a SalI/XbaI decarboxylase fragment into the S. cerevisiaelow copy episomal vector pRS414, which was restriction enzyme digestedwith SalI and SacI.

The resulting plasmids were obtained:

-   pAKP-85: PgaI10-Pae_AT-Tadh2 PgaI2-Pdc_DC-Tpma1-   pAKP-86: PgaI10-Pae_AT-Tadh2 PgaI2-KdcA_DC-Tpma1-   pAKP-87: PgaI10-Vfl_AT-Tadh2 PgaI2-Pdc_DC-Tpma1-   pAKP-88: PgaI10-Vfl_AT-Tadh2 PgaI2-KdcA_DC-Tpma1

Transformation and Growth of S. cerevisiae

S. cerevisiae strain CEN.PK113-3C was transformed with 1 μg of plasmidDNA according to the method as described by Gietz and Woods (Gietz, R.D. and Woods, R. A. (2002). Transformation of yeast by the Liac/SScarrier DNA/PEG method. Methods in Enzymology 350: 87-96). Cells wereplated on agar plates with lx Yeast Nitrogen Base without amino acidsand 2% glucose.

The resulting strains were grown aerobically at 30° C. for 48 hour inVerduyn minimal medium containing 0.05% glucose and 4% galactose.

Preparation of Cell Free Extract

1 ml of potassium phosphate buffer (pH 7) was added to 0.5 g of the cellpellet. This mixture was added to a 2 ml eppendorf tube which contained0.5 g of glassbeads with a diameter of 0.4-0.5 mM. Samples werevigorously shaken with an eppendorf shaker (IKA VIBRAX-VXR) for 20 s.The resulting cell free extract was centrifuged for 5 minutes at 14000rpm and 4° C. The supernatant was used for enzyme activity assays.

Enzymatic Reactions for Conversion of AKP to 6-ACA in Presence ofDecarboxylase and Aminotransferase Co-Expressed in S. Cerevisiae

A reaction mixture was prepared comprising 50 mM AKP, 5 mM magnesiumchloride, 100 μM□ pyridoxal 5′-phosphate, 1 mM thiamine diphosphate and50 mM racemic α-methylbenzylamine in 100 mM potassium phosphate buffer,pH 6.5. 1.6 ml of the reaction mixture were dispensed into a reactionvessel. To start the reaction, 0.4 ml of the cell free extract from S.cerevisiae containing decarboxylase and aminotransferase were added, toeach of the reaction vessels. Reaction mixtures were incubated with amagnetic stirrer at 37° C. Furthermore, a chemical blank mixture(without cell free extract) and a biological blank (S. cerevisiae) wereincubated under the same conditions. Samples, taken after 19 hours ofincubation, were analysed by HPLC-MS. The results are summarised in thefollowing table.

TABLE 8 6-ACA formation from AKP using a micro-organism as a biocatalystBiocatalyst 6-ACA concentration [mg/kg] S. cerevisiae pAKP-85 63 S.cerevisiae pAKP-86 226 S. cerevisiae pAKP-87 1072 S. cerevisiae pAKP-884783 S. cerevisiae 3.9 (biological blank) None (chemical blank) 1.3

Enzymatic Reactions for Conversion of Alpha-Ketopimelic Acid toAlpha-Aminopimelic Acid

A reaction mixture was prepared comprising 10 mM alpha-ketopimelic acid,20 mM L-alanine, and 50 μM□ pyridoxal 5′-phosphate in 50 mM potassiumphosphate buffer, pH 7.0. 800 μl of the reaction mixture were dispensedinto each well of the well plates. To start the reaction, 200 μl of thecell lysates were added, to each of the wells. Reaction mixtures wereincubated on a shaker at 37° C. for 24 h. Furthermore, a chemical blankmixture (without cell free extract) and a biological blank (E. coliTOP10 with pBAD/Myc-His C) were incubated under the same conditions.Samples were analysed by HPLC-MS. The results are summarised in thefollowing table.

TABLE 9 AAP formation from AKP in the presence of aminotransferases AAPconcentration [mg/kg] Biocatalyst (after 24 hrs) E. coliTOP10/pBAD-Vfl_AT 3.7 E. coli TOP10/pBAD-Psy_AT 15.8 E. coliTOP10/pBAD-Bsu_gi16078032_AT 11.2 E. coli TOP10/pBAD-Rsp_AT 9.8 E. coliTOP10/pBAD-Bsu_gi16080075_AT 4.6 E. coli TOP10/pBAD-Lpn_AT 5.4 E. coliTOP10/pBAD-Neu_AT 7.7 E. coli TOP10/pBAD-Ngo_AT 5.1 E. coliTOP10/pBAD-Pae_gi9951299_AT 5.6 E. coli TOP10/pBAD-Rpa_AT 5.4 E. coliTOP10 with pBAD/Myc-His C 1.4 (biological blank) None (chemical blank) 0

It is shown that the formation of AAP from AKP is catalysed by thebiocatalyst.

Chemical Conversion of AAP to Caprolactam

To a suspension of 1.5 grams of D,L-2-aminopimelic acid in 21 mlcyclohexanone, 0.5 ml of cyclohexenone was added. The mixture was heatedon an oil bath for 20 h at reflux (approximately 160° C.). After coolingto room temperature the reaction mixture was decanted and the clearsolution was evaporated under reduced pressure. The remaining 2 grams ofbrownish oil were analyzed by ¹H-NMR and HPLC and contained 0.8 wt %caprolactam and 6 wt % of cyclic oligomers of caprolactam.

1. (canceled)
 2. Method for preparing 6-aminocaproic acid, wherein the6-aminocaproic acid is prepared from 5-formylpentanoate, using at leastone biocatalyst. 3-25. (canceled)